Optimisation of diallyl disulfide concentration and effect of soil condition on urease inhibition

Abstract

Diallyl disulfide (DADS) is an organosulfur compound that is expected to exhibit inhibitory property against urease similar to allicin, affirmed through preliminary study. The research aims to optimize DADS’s concentration and duration of inhibition and observe the effect of soil moisture, temperature and pH on the inhibitory action of DADS. The calorimetric method was applied to optimize DADS’s concentration significant for inhibition. High-performance liquid chromatography was used to quantify DADS present under different parameters relevant to selected soil conditions. The results obtained suggested that 5% of DADS/urea-N (w/w) treatment exhibited the highest urea hydrolysis reduction by 27.91% compared to the control sample at the end of 30 days. ANOVA results observed urea hydrolysis is significantly slower by applying 5% DADS/urea-N (w/w) treatment compared to the other DADS treatments. DADS also retained its original form longer in soil when the soil conditions were altered to 15% moisture content, 20 °C and pH 4. The findings exhibit the potential of DADS as a natural based inhibitor that is effective at low concentrations, compatible with urea and chemically stable.